The basic requirements for polymeric materials in some areas of medical application are that they be hydrophilic, soft and oxygen-permeable. The prior art teaches the use of many different polymeric materials in these areas such as in contact lenses, intraocular lens and other prosthetic devices. Although these polymers possess certain desirable properties for their specific medical application, they suffer from other undesirable characteristics which reduce their utility.
In contact lens area, the hard lens material, polymethyl methacrylate (PMMA), is durable but relatively impermeable to oxygen and further suffers from being rigid and hydrophobic. The hydrogel contact lens based on hydrophilic polymers such as polyhydroxyethyl methacrylate (Poly HEMA) are soft but with poor durability and dimensional stability. It also does not have enough oxygen permeability.
Another polymeric material is silicone rubber, one kind of polysiloxane, which can also be used in contact lens and other prosthetic devices. Although it is soft, resilient and is highly gas permeable, it is hydrophobic.
As compared to the hard lens material, PMMA, the copolymers taught in the patent to Gaylord, U. S. Pat. No. 3,808,178, for contact lens fabrication have relatively high oxygen permeability, but suffer from being rigid and relatively hydrophobic.
Accordingly, it would be highly useful in a number of medical applications to provide a polymeric material having increased hydrophilicity, softness after hydration, and oxygen permeability. For contact lenses, this material provides a combination of properties that are close to an ideal combination of properties of the best features of the hard lens material, PMMA, soft lens material, Poly HEMA, silicone rubber and the Gaylord copolymer lenses. For other prosthetic devices, features such as increased hydrophilicity, softness after hydration and gas permeability are also very useful and desirable. The inventive composition has been found to provide above features.